Hydrocarbon compositions



Patented July 23, 1957 HYDROCARBON COMPOSITIONS Theodore R. Lusebrink,Concord, and Stanley L. Cosgrove, Martinez, Calif., assignors to ShellDevelopment Company, New York, N. Y., a corporation of Delaware NoDrawing. Application August 24, 1955, Serial No. 530,418

7 Claims. (CI. 4462) This invention relates to improved hydrocarboncompositions -boiling substantially within the gasoline boiling range,particularly such compositions designed to be used as fuels in internalcombustion engines.

Commercial hydrocarbon compositions boiling in the gasoline boilingrange invariably contain small amounts of water, either dissolved ordispersed in the product. This is because it is virtually impossible toprevent contact of the product with water during blending operations,storage and transportation to the consumer. Also, even if the greatestprecautions to prevent any such contact were taken, water would still beabsorbed from the atmosphere. The presence of a small amount of water assuch is not normally deleterious; however, when the product is cooled,ice particles are often formed.

The formation of ice in such hydrocarbon products is usually at leasttroublesome and often is extremely dangerous. For example, allgasoline-powered vehicles are normally provided with filters, such asfilter screens and micronic filters, in the fuel system, so as toprevent the passage of solid contaminants, for example, small particlesof rust, into the engine. When ice is formed in the gasoline used, itwill often plug the filters, thus stopping the flow of fuel to theengine. In the case of vehicles operating on the ground or Watersurface, this is at least inconvenient; but in aircraft such stoppage,of course, involves a grave risk to human life. Because of this danger,most aircraft are provided with an automatic bypass around the filters.However, on the opening of the -by-pass, the ice is passed through toinjector mechanisms and the like, which contain close and criticaltolerances. Here, the ice causes still further difiiculties, includingmalfunctioning of these mechanisms.

Another fuel system mechanism which is particularly prone tomalfunctioning due to plugging with ice is the carburetor. At this pointin the fuel system, additional moisture is introduced from the air forcombustion. Even though both liquid fuel and air temperatures are above32 F., the evaporation of the fuel in the carburetor will often cool thesystem to 32 F. or below, especially soon after starting the engine,whereupon ice will form and will frequently cause the engine to stallbecause of the blocking of fuel and air passages by the ice.

Other hydrocarbon products boiling within the gasoline boiling rangebesides gasoline itself are susceptible to difiiculties due to theformation of ice therein, for example, mineral spirits, cleanersnaphtha, VM&P naphtha and other specialty products such as benzene,toluene and xylenes, isopentane and the like.

Heretofore, these difficulties have sometimes been alleviated byincorporating into the hydrocarbon product certain water-solublefreezing point depressants, such as alcohols, including glycols, or thelike. However, this requires relatively large concentrations of thefreezing point depressant, for example, from about 0.1% to as high as 2or 3% by volume. These large concentrations are not only uneconomicalbut also often adversely affect the chemical and physical properties ofthe product. Ad-

cooled. However,

ditionally, the high water solubility of these compounds makes themsusceptible to removal from the hydrocarbon product by the leachingaction of the free Water with which the product usually comes in contactduring storage. Furthermore, such water-soluble products, whenincorporated into the hydrocarbon product, act as solubilizers forwater, thus actually increasing the amount of water which the productwill absorb during commercial handling. Although this is by no meansdesirable, the alcohols, for example isopropyl alcohol, still aresomewhat effective in decreasing the incidence of stalling ofautomobiles due to carburetor icing. But in the case of aircraftapplications, wherein filter clogging is particularly critical, andtemperatures are unusually low, the increased concentration of water inthe gasoline over-balances the benefit of the freezing point depressant,so the addition of the latter often aggravates rather than alleviatesthe problem.

It is accordingly a principal object of this invention to provide animproved composition of hydrocarbons boiling within the gasoline boilingrange. A more particular object is to provide such a composition whichhas improved characteristics with respect to ice formation therein. Afurther object of the invention is to provide a gasoline fuelcomposition with improved anti-icing characteristics. Still further anobject of the invention is to provide a hydrocarbon composition withimproved characteristics with respect to ice formation therein and whichrequires neither a water soluble anti-icing additive nor a highconcentration of an anti-icing additive. Other objects will be apparentfrom the description of the invention.

It has now been discovered that these and other objects are attained bythe addition, to a hydrocarbon product boiling within the gasolineboiling range, of an extremely small concentration, for example, lessthan 100 parts per million (wt), organic polymers, to be described withparticularity hereinafter.

The exact way that the polymeric additive alleviates icing difiicultiesis not known. Since the additive is not water soluble, it probably doesnot act strictly as a freezing point depressant, and so it may notactually prevent the formation of ice when the hydrocarbon product iseven if the ice still forms, it is clear that the presence vents, or atleast reduces, plugging of screens and interference with the operationof pumps, injector mechanisms, carburetors, and the like.

The hydrocarbon base material which is the major component of thecomposition of the invention can be any hydrocarbon or mixture ofhydrocarbons boiling substantially within the gasoline boiling range;that is, those with normal boiling points from about 30 F. to about 450F. The invention is particularly directed to mixtures of hydrocarbonswithin an ASTM boiling range of from about F. to about 425 R, such asgasoline, and especially such as aviation gasoline, which normally hasan ASTM boiling range of from about F. to about 350 F.

The polymeric additive of the invention is a hydrolyzed reaction productof a vinyl ester of a lower molecular weight allkyl carboxylic acid, ora mixture of such esters, and 'an acyclic alpha-monoolefinic hydrocarboncontaining a terminal CH2=CH group and containing at least 10 and nomore than 42 carbon atoms, or a mixture of such alpha-olefins. Thehydrolyzed reaction product is a mixture of compounds having an averagemolecular weight of from about 4000 to about 100,000, each moleculethereof containing a linear backbone hydrocarbon chain of from about 40to about 4000 carbon atoms substituted on about half the carbon atoms ofthis chain of certain highly-branched oil-soluble of the additive of theinvention preby randomly or uniformly located polar and non-polargroups, the polar groups being hydroxyl groups and alkanoyloxy where R=Hor alkyl) groups, the alkyl subgroup of the latter containing no morethan 4 carbon atoms, at least about 30% of the polar groups beinghydroxyl groups, and the non-polar groups being acylic hydrocarbylgroups containing from 8 to 40 carbon atoms, wherein the ratio of thenumber of polar groups to the number of nonpolar groups is from about0.511 to about 10:1.

The alkyl groups of the copolymer are, of course, determined by theparticular acyclic alpha-monoolefin used. Since the terminal CH2=CH-group of this monomer enters the backbone chain of the copolymer, thealkyl group derived from a particular olefin molecule will be theremainder of the molecule. It is preferred that these alkyl groups bestraight chain groups and it is also preferred that they contain'atleast 10 carbon atoms, especially at least 12 carbon atoms. However,these groups should not be too long and preferably should contain nomore than 30 carbons. Still better results will be obtained with alkylgroups containing no more than about 20 carbon atoms.

The acid from which the vinyl ester is derived can generally be any ofthe lower molecular weight alkyl carboxylic acids, preferablymono-carboxylic acids, containing up to 5 carbon atoms. The vinyl estercan thus be vinyl formate, vinyl acetate, vinyl propionate or the like.Vinyl acetate is a cheap, readily available and especially preferableester for the purposes of the invention.

It is preferred that the average molecular weight of the hydrolyzedcopolymer be at least 8000 and even better results will be generallyobtained with molecular weights above about 10,000. Oh the other hand,although molecular weights up to about 100,000 can be used, betterresults will be generally obtained with average molecular weights nogreater than about 50,000, and especially no greater than 25,000.

Generally, superior results are obtained with hydrolyzed 'copolymers ofthe invention wherein the ratio of the number of polar groups to thenumber of non-polar groups (i. e., the mole ratio of the vinyl ester tothe alpha-olefin in the copolymer before hydrolysis) is at least 1: 1,especially at least 3: 1. On the other hand, this ratio is preferablynot greater than 8:1, 'and especially not greater than 5:1. i

The degree of hydrolysis of the copolymer, of course, determines theproportion of the polar groups which will be hydroxyl groups. It ispreferred that at least 50%, and especially at least 80%, of the polargroups be bydroxyl groups. Generally, best results will be obtained ifnearly all are hydroxyl groups; however, practical considerations in thehydrolysis of the copolymer will usually limit the economic proportionof hydroxyl groups to about 90 or 95% of the total of the hydroxyl andalkanoyloxy groups of the hydrolyzed copolymer.

The copolymer can be readily prepared by reacting the vinyl ester withthe alpha-olefin in the presence of a free radical catalyst orinitiator. Generally, an oxygencontaining catalyst is preferred, i. e.,a compound containing two directly linked oxygen atoms, preferably anorganic peroxide, for example, ditertiarybutyl peroxide, benzoylperoxide or dichlorobenzoyl peroxide, but other free radical catalysts,for example, :,0c-3Z0dilSOblltY1'O- nitrile and the like, have beenfound to be effective. Also, the reaction can be made to progress by theuse of actinic radiation, such as ultraviolet light. The concentrationof the catalyst in the reaction mixture can be varied widely, forexample, from as low as 0.01% wt. to wt. or more, based on the weight ofthe reactants initially added. As a general rule, the larger theconcentration of catalyst 7 should be at least about 0.1:1 in order toprovide a sufiicient ratio of polar to non-polar groups in thecopolymer. Best results are obtained if this ratio is at least about05:1 and especially at least about 1.5:1. However, to avoid too high aratio of polar to non-polar groups in the copolymer, this ratio shouldgenerally be not greater than about 10:1 and best results are obtainedif this ratio is not greater than 5:1, especially not greater than2.521. The amounts of excess monomer recovered after the polymerizationreaction will, of course, indicate the ratio of the original monomerswhich have entered the copolymer. Accordingly, the ratio of the numberof alkanoyloxy groups to the number of alkyl groups in the copolymer canbe adjusted at will by varying the original ratio of the two monomersinitially charged to the reaction.

The temperature of the reacting mixture can be selected for conveniencein order to effect a substantial conversion of the monomers into thecopolymer in a reasonable length of time. Ordinarily, the reaction willprogress satisfactorily at temperatures of from about 50 C. to about 2000., preferred temperatures being from about 70 C. to about C. Thereacting pressure should be sufficient to keep the reactantssubstantially in the liquid phase at the reaction temperature employed.The unreacted monomers and any solvent used can then be distilled offfrom the copolymer product.

Either a batch or a continuous process for the polymerization reactioncan be used. Especially suitable copolymers are obtained when the ratioof the unreacted monomers is kept approximately constant throughout thereaction, as is of course the case in the normal continuous processtechnique. The same advantage can be attained in a batch process bycontinuous or intermittent addition of further amounts of one of themonomers, usually the ester, to the reacting mixture of monomers andcopolymers.

After this copolymer is formed and separated, it must be hydrolyzed to asubstantial extent, otherwise it will not be suitable for the purposesof the invention. By hydrolyzed, we mean that a substantial proportionof the alk anoyloxy groups of the copolymer chain must be converted tohydroxy groups. The way this is accomplished is generally not importantso long as the resulting hydrolyzed copolymer is not contaminated to anygreat extent with the other products of the hydrolysis reaction. Anespecially convenient and effective method of effecting the hydrolysisof the copolymer is to react it with a lower molecular weight alcohol,such as methanol or ethanol, in the presence of a small amount of ahydrolysis catalyst such as an alkali metal alkoxide, or alcoholate, forexample, sodium methoxide (i. e., sodium methylate), and preferably alsoin the presence of a solvent, which can be, for example, either anexcess of the alcohol or an ester of the alcohol and the acid group ofthe vinyl ester monomer, or both. After the hydrolysis reaction hasprogressed to the desired extent, the alkali metal alcoholate isneutralized, for example, with an equivalent amount of glacial aceticacid, and the solvent and the hydrolysis products can then be distilledoff from the hydrolyzed copolymer. Other well known methods ofhydrolyzing polyvinyl esters are generally suitable, such as thosedescribed in U. S. Patents Nos. 2,266,996; 2,464,290; and 2,668,809.Saponification with aqueous sodium hydroxide is efifective but lessdesirable because of the necessity of removing from the hydrolyzedcopolymer the high concentrations of excess sodium hydroxide and theresulting sodium salt of the acid group of the vinyl ester.

than 100 parts per million (wt.).

parts per million.

Besides the hydrolyzed copolymer, the hydrocarbon compositions of theinvention can, and ordinarily will,

contain other additives, such as the usual commercial additives, forexample, antidetonants, such as tetraethyl lead, iron carbonyl,dicyclopentadienyl iron, xylidene and N-methyl aniline, lead scavengers,such as ethylene dibromide and ethylene dichloride, dyes, spark plugantifoulants, such as tricresyl phosphate and dimethyl xylyl phosphate,combustion modifiers, such as alkyl boronic acids and lower alkylphosphates and phosphites, oxidation inhibitors, such asN,Ndisecondarybutyl-phenylenediamine, N-n-butyl-p-aminophenol and2,6-ditertiarybutyl-4-methylphenol, metal deactivators, such as N,N'-

disalicylal-1,2-propanediamine, and rust inhibitors such as polymerizedlinoleic acids and N,C-disubstituted imidazolines.

The invention is illustrated in the following examples, which, however,should not be considered limitations thereof.

EXAMPLE I A hydrolyzed copolymer additive suitable for the purposes ofthe invention was prepared as follows:

Freshly distilled vinyl acetate was added to a mixture of straight chainalpha-olefin hydrocarbons containing 4% v. (3131126, 19% V. C14H2s, 4%v. C15H30, 45% v. Ciel-132, 3% V. C1'1H34 and V. C18H36, With theremainder being minor amounts of saturated hydrocarbons in the samecarbon number range, in the proportion of 1.9 mols of the acetate permol of the olefin. To this mixture was added 1% w. benzoyl peroxide asan initiator. The mixture was then stirred at 80 C. for 16 hours. Atthis time the unreacted material was distilled off to a temperature of200 C. at 18 mm. Hg absolute pressure. The remaining copolymer amountedto approximately 61% by weight of the monomers initially charged. Thecopolymer was cooled and analyzed. The acetate to olefin mol ratio inthe copolymer was 3.95 to l, and the ester value was 0.71 equivalent per100 grams.

The copolymer was then hydrolyzed as follows: To 100 parts by weight ofthe copolymer was added 72 parts of anhydrous mefllyl alcohol, 0.72 partof water and 1 part of sodium methylate. This mixture was heated andmaintained at 65 C. with refluxing for 2 hours. The mixture was thencooled and to it was added approximately 10% excess of glacial aceticacid, based on the stoichiometric ratio of acetic acid to the sodiummethylate previously added. The excess methanol and the hydrolysisproduct methyl acetate were distilled off and the hydrolyzed copolymerrecovered. The product was analyzed and found to have a hydroxyl valueof 0.64 equivalent per 100 grams,

and a ratio of hydroxyl groups to ester groups of about 4 to 1. Thus,the copolymer had been about 80% hydrolyzed. The product was a clear,light brown, oil

soluble solid with a molecular weight of about 15,000.

EXAMPLE H filled with water. The waiter thus displaced is introducedinto a second glass vessel, initially filled with the hydrocarbonproduct to be tested. The hydrocarbon product thus displaced from thesecond glass vessel is passed through a heat exchanger, where itstemperature is reduced to the desired level, usually between about 0 F.and 20 F., and immediately thereafter through a 10 micron paper filter(Bendix Skinner Division, Bendix Aviation Corporation, Part No.568,509). In this manner the hydrocarbon product is kept in contact withwater, and air is excluded, thus avoiding any change in waterconcentration in the hydrocarbon product. The flow rate of thehydrocarbon product through the filter was held constant in all tests at38 cc. per minute. The pressure difierential across the filter at anytime is therefore a measure of the degree to which the filter is pluggedwith ice.

The elapsed time before this differential pressure has reached 16 cm. Hgwas selected as a'measure of the ability of the hydrocarbon product toavoid plugging of the filter with ice. The higher this figure, ofcourse, the better the hydrocarbon product.

It has been found that variations in filter temperature between about 0F. and 20 F. do not have a substantial effect on the elapsed time beforefilter plugging in this test.

The base product selected for the tests in this example was aspecification MIL-F-5572 115/145 grade aviation gasoline, containingonly the specification additives, tetraethyl lead, ethylene dibromideand 2,6-ditertiarybutyl-4 methylphenol oxidation inhibitor.

The results btained in these tests are presented in Table I, listed inthe chronological order obtained. Additive A, listed in Table I, is thehydrolyzed copolymer obtained in Example I. Additive B is aC,N-disubstituted imidazoline of the general structural formula:

/NOH2 C :4( 2)1uC N-CHa HOCHr-CHz which compound is a corrosioninhibitor.

40 Table I Concentration,

p. p. 111. (wt) Average Temperature at Filter, F.

Time, Minutes, To 16 cm. Hg Ap Test No. Additive The compositions of theinvention are thus seen to be superior to the usual commercial gasolineby several magnitudes, and that the presence of a corrosion inhibitordoes not detract this benefit.

EXAMPLE I III In order to prove the benefits of the compositions of theinvention in commercial equipment, they were tested in a full-scalemock-up of the fuel system of the model 1049C Super Constellationaircraft. The equipment and procedure for this test is as follows: Thefuel to be tested is contained in a well-insulated 1000 gallon tankequipped with internal cooling coils and fuel booster pump. A oneinchaluminum fuel line is led into an insulated cold box approximately 20 x3 x 3 feet which contains all other components of the system. Theatmosphere within the box is maintained at a low temperature bycirculation of carbon dioxide through the box via a fan and duct system.The fuel line is feet long and is connected to a 10 micron paper filterwhich is provided with a by-pass which mate opens a t about 19 cm. Hgdifferential pressure. The line t n ead i hrqug a e hani ally d e e pmp, through a flowjrneter, to a 200 mesh wire screen filter, alsoprovided witha by pass opening at about 16 cm. Hg, then through the fuelmaster control and finally from the cold box tounderground storagetanks. The fuel is tested on a once-through basis.

The base fuel in each test was a specification MIL-F- 5572 115/145 gradeaviation gasoline, containing only the specification additives,tetr-aethyl lead, ethylene dibromide and2,6-ditertia-ry-butyl-4-methylphenol oxidation inhibitor. The 1000gallons of test fuel is first agitated with gallons of water and the airin the space above the fuel is saturated with water for.8 to 12 hoursbefore a test. The water is then drawn off and the fuel is pumped to the1000 gallon test tank through a 10 micron bronze filter. This treatmentsaturates the fuel with water at the desired temperature but excludesany entrained separate water. The fuel is-then cooled without stirring,to avoid ice crystallization on the cooling coils or the sides of thetank. The refrigerant is turned off when the fuel is at the desired testtemperature (-10 F. for these tests) to eliminate dehumidification ofthe fuel by the exposed coils as the fuel is used in the test. The fuelis then pumped through the system in the cold box, with the temperatureof the carbon diox ide atmosphere therein being set at 40 F., allvariables being controlled exactly as in a commercial aircraft under theselected conditions. A constant fuel flow is maintained at 1900 poundsper hour by adjustment of the throttle valve on the outlet of the coldbox. It has been found that no icing occurs anywhere downstream of the10 micron filter until it has iced and the bypass is opened.

With the base gasoline the time required to plug the 10 micron filtersufliciently to open its bypass was 57 minutes. In only 2 additionalminutes the 200 mesh screen plugged sufliciently to open its bypass.

When the same base gasoline, but now containing 10 parts per million byweight of the copolymer of Example I, was used in this test, the timebefore the 10 micron filter was plugged sufficiently to open its bypasswas 99 minutes, nearly double the time with the base fuel alone. Moresurprising, however, was the fact that the additional time necessary toplug the 200 mesh screen sufficiently to open its bypass was extended to45 minutes, over times the time with the base gasoline alone.

EXAMPLE IV In order to determine the benefits of the additives of theinvention in respect to icing in carburetors, the following test wasadopted:

A standard ASTM-CFR fuel research engine was fitted with a Chevroletcarburetor (Carter, Model No. WA- 1-4135). Intake air for the engine wasadjusted for the tests to a constant temperature and humidity at the airinlet to the carburetor of 41 F. and 75 percent relative humidity,respectively, a combination of atmospheric conditions which is known tolead to carburetor icing very frequently in practice. Since it is alsowell known that stalling due to carburetor icing in automobiles mostfrequently occurs soon after a cold start and atr a time when the enginespeed is reduced to idling, for example, as an automobile is stopped ata street intersection, these circumstances were simulated, and the testprocedure standardized, by operating the test engine on the testgasoline with the throttle adjusted to open position until thetemperature of the body of the carburetor is reduced to 36 F. With thebase gasoline selected for thetests in this example, an automotivegasoline, having a 50% ASTM boiling point of 200 F. and containingftheusual commercial additives but no alcohol or other antieicing agent, thetime necessary to reduce the temperature of the body'of the carburetorto 36 F. was uniformly about 3 minutes. 'At this, time, the throttlevalve was closed to the idling position. The time V 8 interval thenexpiring until the engine stalled is the measure of the tendencyof thetest gasoline composition .to prevent stalling due to carburetor icingand is called the stall time of thetest gasoline composition.Compositions with greater stall times are, of course, .superior to thosewith lesser stall times.

To provide data which are more meaningful in respect to the value of thegasoline compositions of the invention, a large number of tests weremade on the base gasoline alone and also on the base gasoline with 1% byvolume of isopropyl alcohol (a well known freezing point depressant typeof gasoline anti-icing additive). The stall time obtained with the basegasoline and an anti-icing additive was divided by the stall timeobtained with the base gasoline alone, thus giving a stall time ratiowhich is a direct measure of magnitude of the anti-icing benefit of theadditive. The results of these tests are shown in Table II.

Additive A of Table II is a hydrolyzed vinyl acetate/ l-octadeceneprepared with the procedure of Example I except that the ratio of vinylacetate to l-octadecene charged was 1.6:1, the polymerization reactionwas allowed to progress for 24 hours, the yield of copolymer was 40.5%,and the hydrolysis was effected by refluxing the copolymer for 24 hourswith parts of 3A denatured alcohol in which 0.25 part of metallic sodiumhad been dissolved for each parts by weight of copolymer. The ratio ofpolar groups (hydroxyl and acetate) to non-polar groups in thehydrolyzed copolymer was 3.5:1, the hydroxyl value was 0.72 equivalentper 100 grams, the degree of hydrolysis was 85.6% (i. e., 85.6% of thetotal number of hydroxyl and acetate groups consists of hydroxylgroups), and the molecular weight was about 16,500.

Additive B of Table II was also a vinyl acetate alpha- 'olefin preparedwith the procedure of Example I, but in this case the alpha-olefin wasl-dodecene, the ratio of vinyl acetate to l-dodecene charged was 0.835:1, the polymerization reaction was allowed to progress for 24 hours,the yield of copolymer was 27%, and the hydrolysis was effected byrefluxing the copolymer with 400 parts of methanol in which 0.25 part ofmetallic sodium had been dissolved for each 100 parts by weight ofcopolymer. The ratio of polar groups (hydroxyl and acetate) to non-polargroups in the hydrolyzed copolymer was 2:1, the hydroxyl value was 0.748equivalent per 100 grams and the degree of hydrolysis was 96% (i. e.,96% of the total number of hydroxyl and acetate groups consists ofhydroxyl groups).

Table II AVERAGE STALL TIME RATIOS [Stall time with anti-icingadditive/Stall time with base gasoline] Average Ant1-Icmg AdditiveConcentration Stall Time Ratio Isopropyl alcohol 1 v 1. 7 Additive A 50p m- 1. 8 Additive B 50 p. p m 1. 7

substantially in the gasoline boiling range and at least 1 and less than100 parts per million by weight of an at least partially hydrolyzedreaction product of a vinyl ester of. a lower molecular weight alkylcarboxylic acid and an acyclic monoolefinic hydrocarbon material with aterminal CH2=CH group and containing from 10 to 40 carbon atoms permolecule, said reaction product, before hydrolysis, containing saidvinyl ester and said monoolefinic hydrocarbon material in a mol ratio offrom about 0.5 :1 to about 10:1, said hydrolyzed reaction product havingan average molecular weight of about 4000 to about 100,000.

2. A gasoline composition in accordance with claim 1, wherein saidhydrolyzed reaction product, containing polar groups consistingessentially of hydroXyl groups and alkanoyloxy groups, contains hydroxylgroups in a proportion of at least 30% of the total of said polargroups.

3. A gasoline composition in accordance with claim 2, wherein the vinylester is vinyl acetate.

4. A gasoline composition in accordance with claim 3, wherein theacyclic monoolefinic hydrocarbon material contains from about 10 toabout 30 carbon atoms per molecule.

5. A gasoline composition in accordance with claim 4, wherein at least80% of the polar groups of the hydrolyzed reaction product are hydroxylgroups and wherein the concentration of the hydrolyzed reaction producttherein is from about 5 to about 50 parts per million by weight.

6. An aviation gasoline composition consisting essentially of ahydrocarbon base material boiling substantially in the aviation gasolineboiling range and from about to about 30 parts per million by weight ofan at least 80% hydrolyzed reaction product of vinyl acetate and amixture of monoolefinic hydrocarbons substantially most molecules ofwhich hydrocarbons have a terminal CHz=CH- group and from about 14 toabout 18 carbon atoms, said reaction product, before hydrolysis,containing said vinyl acetate and said mixture of monoolefinichydrocarbons in a mol ratio of about 4:1 said hydrolyzed reactionproduct having an average molecular weight of from about 4000 to about100,000.

7. A gasoline composition consisting essentially of a hydrocarbon basematerial boiling substantially in the gasoline boiling range and atleast 1 and less than parts per million by weight of an at leastpartially hydrolyzed reaction product of vinyl acetate and a mixture ofmonoolefinic hydrocarbons substantially most molecules of whichhydrocarbons have a terminal CH2=CH- group and from about 14 to about 18carbon atoms, said reaction product, before hydrolysis, containing saidvinyl acetate and said mixture of monoolefinic hydrocarbons in a molratio of from about 3:1 to about 5:1, said hydrolyzed reaction producthaving an average molecular weight of from about 10,000 to about 25,000.

References Cited in the file of this patent UNITED STATES PATENTS2,213,423 Wiezevich Sept. 3, 1940 2,386,347 Roland Oct. 9, 19452,421,971 Sperati June 10, 1947 2,469,737 McNab et a1 May 10, 1949

1. A GASOLINE COMPOSITION CONSISTING ESSENTIALLY OF A MAJOR AMOUNT OF AHYDROCARBON BASE MATERIAL BOILING SUBSTANTIALLY IN THE GASOLINE BOILINGRANGE AND AT LEAST 1 AND LESS THAN 100 PARTS PER MILLION BY WEIGHT OF ANAT LEAST PARTIALLY HYDROLYZED REACTION PRODUCT OF A VINYL ESTER OF ALOWER MOLECULAR WEIGHT ALKYL CARBOXYLIC ACID AND AN ACYCLIC MONOOLEFINICHYDROCARBON MATERIAL WITH A TERMINAL CH2=CH- GROUP AND CONTAINING FROM10 TO 40 CARBON ATOMS PER MOLECULE, SAID REACTION PRODUCT, BEFOREHYDROLYSIS, CONTAINING SAID VINYL ESTER AND SAID MONOOLEFINICHYDROCARBON MATERIAL IN A MOL RATIO OF FROM ABOUT 0.5:1 TO ABOUT 10:1,SAID HYDROLYZED REACTION PRODUCT HAVING AN AVERAGE MOLECULAR WEIGHT OFABOUT 4000 TO ABOUT 100,000.